Waist-to-height ratio is a better metric than the old-school BMI

There's a more precise way to measure body fat, a study finds.

For decades, doctors have used body mass index, or BMI, as the go-to for determining obesity. The measurement—which divides weight by the square of your height—has since been denounced by many experts as too simplistic and inaccurate, since it doesn’t take into account muscle mass and other factors.

To wit: According to BMI, Mr. Olympia Phil Heath would be morbidly obese.

To find a more accurate method, researchers at Leeds Beckett University in England tested five body fat calculation techniques that can be easily done in a doctor’s office.

In their study, the researchers figured out the whole-body fat percentages and visceral (fat around the organs) fat mass of 81 adults by using the highly accurate total-body dual-energy X-ray absorptiometry scanner to establish a baseline. The researchers then tested the subjects again using BMI, waist circumference, waist-to-hip ratio, and waist-to-height ratio.

The results showed that waist-to-height (WHtR) was the most accurate way to forecast body fat and visceral fat, with waist-to-hip (which is often used by lots of trainers) being the worst, and BMI also showing very poor predictions.

"Put simply, it is more important, especially for cardio-metabolic conditions, that your belt notch goes down rather than the reading on the scales."

"Our research has shown that WHtR is a more accurate alternative to these two measures and also a more time-efficient measure,” said study head Michelle Swainson, Ph.D., senior lecturer in exercise physiology in the Carnegie School of Sport at Leeds Beckett. “By introducing this alternative, and more accurate, measure into clinical settings, more men and women would potentially be referred to programs, such as weight management, to receive help in improving their health.”

One simple rule of thumb to reduce risk for chronic diseases like diabetes and cardiovascular disease, and generally live a longer life: Make sure your waist circumference is less than half of your height. "Carrying fat around the abdominal area has been shown to be an independent predictor of all-cause mortality in men and women,” she said. “Put simply, it is more important, especially for cardio-metabolic conditions, that your belt notch goes down rather than the reading on the scales."

Get started whittling that waist down now by trying out one of our beginner programs if you're teetering on the edge of being obese, or get into a more advanced program to get your torso ripped and drop another few inches.